As far as Im concerned the biggest problem with HID kits is people buying 8K+ bulb kits for their cars, bulbs FAR too bright to use on the road! Some Chavwagons look like a Star Wars spaceship reversing towards you, such is the blue glare...
Not big, Not Clever... Standard 4800K or even 6000K kits are brighter yet bearable to most people, anything over even in a projector lense will sear the back of your eyeballs...
As from the 1st of October the Police can pull you and fine you for "dazzling oncoming traffic" and its 3 points and fine plus an enforced MOT pass within 28 days...
Too bright a light will get you noticed by the wrong people for the wrong reasons - and NOBODY wants that...
I have a HID kit fitted on one side of my CBR400RR for one reason - its a Jap import & the standard bulb is a 35/60W, an I4 fitting (Think H4 with tabs at 60/120/180deg), if you fit a 55/60W H4 the increased voltage will melt the dipped beam switchgear!
HID will only pull 35W high or low, so I get to fit a much brighter light without toasting my wiring... I want to fit brighter lights to my dCi to ease my 50 mile commute over Salisbury Plain every day, but if it means Im going to be pulled by Officer Boredplod - Im going to have to cope...
Im not taking sides, perhaps sitting on the fence - but if you fit HID's - be sensible about your bulb choice...